PGR and breast cancer: Significant studies on luteolin’s application in breast cancer were conducted on triple-negative breast cancer (TNBC), which accounts for around 15–20% of all breast cancer cases diagnosed, is more commonly found in younger, African-American women, and is characterized by the lack of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression.